Gabriela is 3 times as old as Michael and is also 20 years older than Michael. How old is Gabriela?
Answer: We can use the given information to write down two equations that describe the ages of Gabriela and Michael. Let Gabriela's current age be $g$ and Michael's current age be $m$ $g = 3m$ $g = m + 20$ Now we have two independent equations, and we can solve for our two unknowns. One way to solve for $g$ is to solve the second equation for $m$ and substitute that value into the first equation. Solving our second equation for $m$ , we get: $m = g - 20$ . Substituting this into our first equation, we get the equation: $g = 3$ $(g - 20)$ which combines the information about $g$ from both of our original equations. Simplifying the right side of this equation, we get: $g = 3g - 60$ Solving for $g$ , we get: $2 g = 60$ $g = 30$.